Hi everyone,
I believe the component is a part of charging circuit (probably some kind of FET or voltage regulator) because the device doesn't charge any more after it fried but still works fine when powered from usb.
Fortunately, component marking isn't gone, but searching for "054610", "054g10", "0546" and "054g" didn't get me any results ;(
Can anyone help on this please?

It's Playstation 3 Dualshock controller (Hong Kong version, I also own USA version and disassembled it, pcb is completely different)
I bet its schematic is not publicly available
Although I was able to find some custom researches on that all of them are related to USA version of controller ;(

Looks like a SOT23-5 package. It could be a single gate or a transistor, but if you can't figure out what it is you have no hope of replacing it even if you have the tools and the skill.

As is common for many manufacturers the parts may be labeled with in house markings that do not correspond to readily available parts. SONY probably does this on purpose to defeat people like you who think that repairing surface mount boards is like the old days of point to point chassis wiring and double sided PC boards.

That pcb is a real cheap chinese double-sided pcb, not multilayer And the package is big enough, I usually have problems with smaller parts like 0603, though that's not about soldering skills, just my weak eyes (and that's why I prefer oldschool through-holes when building my own pcbs).
And to buy a new $60 controller 'cause some small FET burned out... Not my way I was just hoping there's an easy answer on that "what the part question". If not, I'll have some fun drawing the diagram of the charging circuit

I've been researching a charging circuit yesterday and made a diagram. Just a draft, so sorry for its quality. "MCU*" terminals are traces to some pins of MCU IC (no markings on an MCU IC at all so I can't learn anything about it).
U1 IC (SOT-23-5 marked "A121") seems to be a RP110x voltage regulator (or similiar one) featuring "chip enable" input. So it becomes clear that burned out U2 is some sort of Li-ion charging IC. The closest match I found is Microchip MCP73811 but it has completely different SMD marking rules according to Microchip. Also, I'm not sure if pin 5 is input in my case, I suppose it could be an output pin to MCU to read charging status (but on the other hand, MCU may read a battery voltage through ADC, who knows?)
I'll make some further research to learn if pin 5 is input or output. For now I assume pin 1 to be "charge enable" active-high tied to Vout (which matches MCP73811 behavior)
Also, if anyone owns some latest SMD markings database (like Taruta SMD code databook 2012) can you please copy-paste codes of 5-pin packages starting with 05, 054 etc.? I own a 2011 edition book but the controller is manufactured in April, 2012 and I suspect them using some latest chip with marking which is not on 2011 edition book.

That pcb is a real cheap chinese double-sided pcb, not multilayer And the package is big enough, I usually have problems with smaller parts like 0603, though that's not about soldering skills, just my weak eyes (and that's why I prefer oldschool through-holes when building my own pcbs).
And to buy a new $60 controller 'cause some small FET burned out... Not my way I was just hoping there's an easy answer on that "what the part question". If not, I'll have some fun drawing the diagram of the charging circuit

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Except if $60 is what you charge for 20 minutes (1/3 hr) of work you have to ask what your time is worth. Especially if the solution is more important than how you got there.

BTW if you succeed in this quest I really really want to hear about it because you will be the first one that has penetrated the in house marking system for fun and profit. I give you maybe 1 chance in 300.

Hey, I'm from Russia, nobody charges $180/hr here except lawyers and Vladimir Putin
Seriously, first it looked like a simple fix but the harder task makes it more interesting

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Lawyers here charge $350 to $500, so I'm just a mid-level hack. Maybe someday you too can charge big bucks. In any case, if the solution is more important than the result I would try the source. You might get lucky by corresponding with the folks who made the device.

You might get lucky by corresponding with the folks who made the device.

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Ask Sony for schematics? Looks like you have too much faith in humanity for this world

I have charged controller battery with external Li-poly charger and was gaming like hell until it got discharged. Console issued a "Controller discharged" message with U2 desoldered, so it's not U2 who's reporting charging progress.